Final answer:
Available appropriation is indeed the difference between total appropriations and the sum of expenditures and encumbrances in governmental accounting, confirming the statement as True.
Step-by-step explanation:
The term available appropriation is a concept in governmental budgeting and accounting, referring to the funds that are available for an organization to commit or spend in a given fiscal period after accounting for all commitments and expenditures. The statement that 'available appropriation is calculated as the difference between appropriations and the sum of expenditures and encumbrances' is True. Appropriations represent the legal authority granted by a legislative body to incur obligations and make payments out of the government treasury for specific purposes. An encumbrance is a commitment of appropriated funds prior to an actual expenditure being made. The available appropriation is essentially the budget remaining after subtracting both the expenditures (actual spending) and the encumbrances (committed funds) from the total appropriations.